Their latest album, Four, experienced a 51 percent increase in album sales last week, according to Nielsen music. The album jumped 41-33 on the Billboard 200. While Four climbed up the Billboard 200, the band's other three albums -- Midnight Memories, Take Me Home and Up All Night -- re-entered the chart at Nos. 110, 187 and 192, respectively.

As for pure album sales, Midnight Memories saw a 72 percent boost, Take Me Home enjoyed a 95 percent increase, and their first release was treated to a 113 percent jump.

The post-Zayn sales boost is a definite contrast to the previous period (ending March 22, 2015), which saw sales for 1D's albums either decrease or increase less than 5 percent, per Nielsen Music.

The band's current single, "Night Changes," also enjoyed a boost, moving 21 percent more downloads as compared to the previous period, per Nielsen Music.

While a number of the new 1D buyers are presumably people curious about the group in the wake of Zayn's departure, it's entirely possible a few loyal Directioners simply re-bought an album or single to support their beleaguered boys. If there's one thing you can say about One Direction fans, it's that they're loyal.

That being said, 1D's last album, Four, saw their first-week sales tally fail to increase for the first time in their career when it landed last year. While the debut week sales for their first three albums grew larger with each release, Four opened with 387,000, a notable drop from Midnight Memories' 546,000.